The present invention relates generally to traction systems for automotive movers, and more specifically to such a system provided to rail movers or railcar movers for enhancing traction of mover drive wheels when traveling on railroad track in unfavorable weather or track conditions.
Railcar movers are self-propelled machines used in rail yards for switching operations, i.e., moving individual rail cars, or connected strings of cars around the yard as needed to unload cargo and for assembling trains. Railcar movers are provided with large displacement engines for providing significant pushing or pulling power, preferably in the range of 15,000 to 60,000 pounds of traction effort, and often have large drive wheels, either steel rail wheels or industrial rubber-tired wheels, the latter also suitable for road travel or travel within the rail yard off of the railroad track, for moving from one track to another. Rubber-tired wheels, also referred to as rubber tires, provide a higher coefficient of friction on the rail compared with conventional steel rail wheels of the type found on locomotives. This higher coefficient of friction increases the pulling capacity of a given railcar mover.
In addition, railcar movers have rail wheels which are retracted until the mover is properly aligned on the track for pulling or pushing rail cars as needed. At that time, the rail wheels are lowered into engagement with the track under operator control. However, the rail wheels provide only a guiding function, since the propulsion of the railcar mover is achieved by engagement of the drive wheels with the rail head. At each end of the railcar mover is a standard rail coupler which enables the mover to connect or disconnect with selected rail cars under operator control from within an operators cab located on the mover or remotely.
One drawback of rubber tires is that during inclement weather, when the track is wet, or covered with ice or snow, or when there is excessive debris on the rails, such as spilled cargo or recently mowed vegetation, the rubber tires more easily lose traction and slip on the rails. This slippage reduces pulling power and overall operational efficiency of the railcar mover.
Conventionally, this problem has been addressed by providing the railcar mover with a bi-directional sanding system, which distributes sand upon the rail just behind or just ahead of the drive wheels, depending on the direction of travel. However, in practice, sanding units have not proven satisfactory. Accordingly, there is a need for a railcar mover with an enhanced traction system that improves traction when track conditions are slippery.